Yealink SIP-T48U Administrator's Guide

General Features
500
After configuration, you can check the configuration file version information at the path: Menu > Status
> Phone > MAC Version (phone user interface) or Status > Status > Version > MAC Version (web
user interface).
Permitted
Values
String
Default
Blank
Supported
Devices
All phones except T48G, T46G, T42G, T41P and T29G
Parameter
features.custom_version_info <y0000000000xx>.cfg
Description
It configures the version information of the CFG configuration file.
After configuration, you can check the configuration file version information at the path: Menu > Status
> CFG Version (phone user interface) or Status > Status > Version > Configuration Version (web
user interface).
Permitted
Values
String
Default
Blank
Supported
Devices
T48G, T46G, T42G, T41P, T29G
Media Loopback
The SIP RTP media loopback can be used to make test calls to verify the media path between the phone and
server.
RTP packets are looped back toward the source device. In a voice loopback call, an echo is heard at the device ori-
ginating the call.
For more information on media loopback, refer to RFC 6849.
Topic
Media Loopback Configuration
Media Loopback Configuration
The following table lists the parameters you can use to configure media loopback.
Parameter
sip.loopback.enable <y0000000000xx>.cfg
Description
It configures the loopback role for the phone.
Note: After the phone accepts the loopback call, the mute feature will be automatically activated on
the phone.
Permitted
Values
0-Loopback-Mirror, the server initiates a loopback call, and the phone accepts the call and mirrors
(echoes) all received media back to the server.
1-Loopback-Source, the phone can initiate a loopback call as a media source or receive a loopback
call as a loopback mirror.
Default
0
Parameter
sip.loopback_type <y0000000000xx>.cfg
Description
It configures the media loopback type.
Permitted
Values
1-rtp-media-loopback, the packet received by loopback mirror is re-encoded based on the SDP nego-
tiation. The re-encoded content is returned to the loopback source as an RTP packet with payload
type corresponding to the re-encoding format.

Yealink SIP-T48U Specifications

General

Handset type	Wired handset
Product type	IP Phone
Product color	Gray
USB 2.0 ports quantity	USB 2.0 ports have a data transmission speed of 480 Mbps, and are backwards compatible with USB 1.1 ports. You can connect all kinds of peripheral devices to them.
Expansion module support	Yes
Ethernet LAN (RJ-45) ports	2
Display diagonal	7 \
Display resolution	800 x 480 pixels
Lines quantity	- lines
Phonebook capacity	1000 entries
Number of VoIP accounts	16
Voice codecs	AGC, AJB, AMR-WB, CNG, G.711, G.722, G.723.1, G.726, G.729ab, VAD, iLBC
Security algorithms	AES, HTTPS, SRTP, TLS
Ethernet LAN data rates	10, 100, 1000 Mbit/s
Ethernet LAN interface type	Gigabit Ethernet
Front camera	-
AC adapter input voltage	100 - 240 V
Operating temperature (T-T)	0 - 40 °C
Operating relative humidity (H-H)	10 - 95 %
Keypad number of keys	29
Number of handles included	1 pc(s)
Harmonized System (HS) code	85171800

Weight and Dimensions

Width	226 mm
Height	185 mm